Switching power supply is a kind of power supply that uses modern power electronic technology to control the time ratio of switching on and off to maintain a stable output voltage. Switching power supplies are generally composed of pulse width modulation (PWM) control ICs and MOSFETs. Compared with the linear power supply, the cost of both switching power supply and linear power supply increases with the increase of output power, but the rising rate of the two is different. The cost of the linear power supply is higher than the switching power supply at a certain output power point. This point is called the cost reversal point. With the development and innovation of power electronics technology, switching power supply technology is constantly innovating. This cost reversal point is increasingly moving to the low output power end, which provides a broad development space for switching power supplies.
1. In order to realize unattended operation, modern communication switching power supplies are equipped with remote monitoring functions, such as remote signaling, telemetry, and remote control. The signal line interface connected to it has a long communication distance, and is extremely susceptible to accidents such as downtime due to induced lightning damage. According to the requirements of the Ministry of Information Industry, corresponding signal lightning protection devices should be installed for protection.
2. The installation of DC lightning protection device was only proposed in the recently announced lightning protection standard. Because the residual voltage of DC lightning protection device is much lower than that of AC lightning protection device, it can effectively improve the protection of sensitive equipment in communication switching power supply communication station against lightning. The ability of electromagnetic pulse
3. The lightning protection capability of the lightning protection device is closely related to the installation method. It is important that the lead inductance will generate additional residual voltage. The connection between the power line and the lightning protection device and the connection between the lightning protection device and the grounding board should be shortened as much as possible The length of the line.
4. Multi-level arrangement of lightning arresters can reduce the additional residual voltage caused by lead inductance, because the former lightning arrester has discharged most of the lightning current into the ground, and the latter lightning arrester only discharges a small part of the lightning. The reduction of current and lightning current will inevitably lead to the reduction of the additional residual voltage on the lead. In order to ensure the energy coordination of the front and rear stages of the lightning arrester, the length of the power cable between the lightning arrester should not be less than 15 meters, otherwise, a decoupler should be used for energy coordination.
V. Lightning protection of incoming power cables is easy to attract attention, while other power lines entering and leaving communication stations are often overlooked, such as lighting street light lines, tower light power lines, and non-telecommunications facilities leased telecommunication power lines. It is advisable to use solar tower lights at present, which can reduce a lightning intrusion channel. Other outgoing power lines should be within the protection range of the lightning protection system, otherwise special lightning protection measures should be taken.